<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>substr - Perldoc Browser</title>
    <link rel="search" href="https://perldoc.perl.org/opensearch.xml" type="application/opensearchdescription+xml" title="Perldoc Browser">
    <link rel="canonical" href="https://perldoc.perl.org/functions/substr">
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css" integrity="sha384-JcKb8q3iqJ61gNV9KGb8thSsNjpSL0n8PARn9HuZOnIxN0hoP+VmmDGMN5t9UJ0Z" crossorigin="anonymous">
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/10.5.0/styles/stackoverflow-light.min.css" integrity="sha512-cG1IdFxqipi3gqLmksLtuk13C+hBa57a6zpWxMeoY3Q9O6ooFxq50DayCdm0QrDgZjMUn23z/0PMZlgft7Yp5Q==" crossorigin="anonymous" />
    <style>
      body {
        background: #f4f4f5;
        color: #020202;
      }
      .navbar-dark {
        background-image: -webkit-linear-gradient(top, #005f85 0, #002e49 100%);
        background-image: -o-linear-gradient(top, #005f85 0, #002e49 100%);
        background-image: linear-gradient(to bottom, #005f85 0, #002e49 100%);
        filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ff005f85', endColorstr='#ff002e49', GradientType=0);
        background-repeat: repeat-x;
      }
      .navbar-dark .navbar-nav .nav-link,
      .navbar-dark .navbar-nav .nav-link:focus { color: #fff }
      .navbar-dark .navbar-nav .nav-link:hover { color: #ffef68 }
      #wrapperlicious {
        margin: 0 auto;
        font: 0.9em 'Helvetica Neue', Helvetica, sans-serif;
        font-weight: normal;
        line-height: 1.5em;
        margin: 0;
        padding: 0;
      }
      #wrapperlicious h1 { font-size: 1.5em }
      #wrapperlicious h2 { font-size: 1.3em }
      #wrapperlicious h3 { font-size: 1.1em }
      #wrapperlicious h4 { font-size: 0.9em }
      #wrapperlicious h1, #wrapperlicious h2, #wrapperlicious h3,
      #wrapperlicious h4, #wrapperlicious dt {
        color: #020202;
        margin-top: 1em;
        margin-bottom: 1em;
        position: relative;
        font-weight: bold;
      }
      #wrapperlicious a { color: inherit; text-decoration: underline }
      #wrapperlicious #toc { text-decoration: none }
      #wrapperlicious a:hover { color: #2a2a2a }
      #wrapperlicious a img { border: 0 }
      #wrapperlicious :not(pre) > code {
        color: inherit;
        background-color: rgba(0, 0, 0, 0.04);
        border-radius: 3px;
        font: 0.9em Consolas, Menlo, Monaco, monospace;
        padding: 0.3em;
      }
      #wrapperlicious dd {
        margin: 0;
        margin-left: 2em;
      }
      #wrapperlicious dt {
        color: #2a2a2a;
        font-weight: bold;
        margin-left: 0.9em;
      }
      #wrapperlicious p {
        margin-bottom: 1em;
        margin-top: 1em;
      }
      #wrapperlicious li > p {
        margin-bottom: 0;
        margin-top: 0;
      }
      #wrapperlicious pre {
        border: 1px solid #c1c1c1;
        border-radius: 3px;
        font: 100% Consolas, Menlo, Monaco, monospace;
        margin-bottom: 1em;
        margin-top: 1em;
      }
      #wrapperlicious pre > code {
        display: block;
        background-color: #f6f6f6;
        font: 0.9em Consolas, Menlo, Monaco, monospace;
        line-height: 1.5em;
        text-align: left;
        white-space: pre;
        padding: 1em;
      }
      #wrapperlicious dl, #wrapperlicious ol, #wrapperlicious ul {
        margin-bottom: 1em;
        margin-top: 1em;
      }
      #wrapperlicious ul {
        list-style-type: square;
      }
      #wrapperlicious ul ul {
        margin-bottom: 0px;
        margin-top: 0px;
      }
      #footer {
        font-size: 0.8em;
        padding-top: 0.5em;
        text-align: center;
      }
      #more {
        display: inline;
        font-size: 0.8em;
      }
      #perldocdiv {
        background-color: #fff;
        border: 1px solid #c1c1c1;
        border-bottom-left-radius: 5px;
        border-bottom-right-radius: 5px;
        margin-left: auto;
        margin-right: auto;
        padding: 3em;
        padding-top: 1em;
        max-width: 960px;
      }
      #moduleversion { float: right }
      #wrapperlicious .leading-notice {
        font-style: italic;
        padding-left: 1em;
        margin-top: 1em;
        margin-bottom: 1em;
      }
      #wrapperlicious .permalink {
        display: none;
        left: -0.75em;
        position: absolute;
        padding-right: 0.25em;
        text-decoration: none;
      }
      #wrapperlicious h1:hover .permalink, #wrapperlicious h2:hover .permalink,
      #wrapperlicious h3:hover .permalink, #wrapperlicious h4:hover .permalink,
      #wrapperlicious dt:hover .permalink {
        display: block;
      }
    </style>
    <!-- Global site tag (gtag.js) - Google Analytics -->
    <script async src="https://www.googletagmanager.com/gtag/js?id=G-KVNWBNT5FB"></script>
    <script>
      window.dataLayer = window.dataLayer || [];
      function gtag(){dataLayer.push(arguments);}
      gtag('js', new Date());

      gtag('config', 'G-KVNWBNT5FB');
      gtag('config', 'UA-50555-3');
    </script>
  </head>
  <body>
    <nav class="navbar navbar-expand-md navbar-dark bg-dark justify-content-between">
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <a class="navbar-brand" href="https://perldoc.perl.org/">Perldoc Browser</a>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item dropdown text-nowrap">
        <a class="nav-link dropdown-toggle" href="substr.html#" id="dropdownlink-stable" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">5.35.0</a>
        <div class="dropdown-menu" aria-labelledby="dropdownlink-stable">
          <a class="dropdown-item" href="https://perldoc.perl.org/functions/substr">Latest</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.38.2/functions/substr">5.38.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.38.1/functions/substr">5.38.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.38.0/functions/substr">5.38.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.36.3/functions/substr">5.36.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.36.2/functions/substr">5.36.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.36.1/functions/substr">5.36.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.36.0/functions/substr">5.36.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.34.3/functions/substr">5.34.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.34.2/functions/substr">5.34.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.34.1/functions/substr">5.34.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.34.0/functions/substr">5.34.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.32.1/functions/substr">5.32.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.32.0/functions/substr">5.32.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.30.3/functions/substr">5.30.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.30.2/functions/substr">5.30.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.30.1/functions/substr">5.30.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.30.0/functions/substr">5.30.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.28.3/functions/substr">5.28.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.28.2/functions/substr">5.28.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.28.1/functions/substr">5.28.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.28.0/functions/substr">5.28.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.26.3/functions/substr">5.26.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.26.2/functions/substr">5.26.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.26.1/functions/substr">5.26.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.26.0/functions/substr">5.26.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.24.4/functions/substr">5.24.4</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.24.3/functions/substr">5.24.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.24.2/functions/substr">5.24.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.24.1/functions/substr">5.24.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.24.0/functions/substr">5.24.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.22.4/functions/substr">5.22.4</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.22.3/functions/substr">5.22.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.22.2/functions/substr">5.22.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.22.1/functions/substr">5.22.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.22.0/functions/substr">5.22.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.20.3/functions/substr">5.20.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.20.2/functions/substr">5.20.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.20.1/functions/substr">5.20.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.20.0/functions/substr">5.20.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.18.4/functions/substr">5.18.4</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.18.3/functions/substr">5.18.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.18.2/functions/substr">5.18.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.18.1/functions/substr">5.18.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.18.0/functions/substr">5.18.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.16.3/functions/substr">5.16.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.16.2/functions/substr">5.16.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.16.1/functions/substr">5.16.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.16.0/functions/substr">5.16.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.14.4/functions/substr">5.14.4</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.14.3/functions/substr">5.14.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.14.2/functions/substr">5.14.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.14.1/functions/substr">5.14.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.14.0/functions/substr">5.14.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.12.5/functions/substr">5.12.5</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.12.4/functions/substr">5.12.4</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.12.3/functions/substr">5.12.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.12.2/functions/substr">5.12.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.12.1/functions/substr">5.12.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.12.0/functions/substr">5.12.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.10.1/functions/substr">5.10.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.10.0/functions/substr">5.10.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.9/functions/substr">5.8.9</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.8/functions/substr">5.8.8</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.7/functions/substr">5.8.7</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.6/functions/substr">5.8.6</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.5/functions/substr">5.8.5</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.4/functions/substr">5.8.4</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.3/functions/substr">5.8.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.2/functions/substr">5.8.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.1/functions/substr">5.8.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.8.0/functions/substr">5.8.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.6.2/functions/substr">5.6.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.6.1/functions/substr">5.6.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.6.0/functions/substr">5.6.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.005_04/functions/substr">5.005_04</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.005_03/functions/substr">5.005_03</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.005_02/functions/substr">5.005_02</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.005_01/functions/substr">5.005_01</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.005/functions/substr">5.005</a>
        </div>
      </li>
      <li class="nav-item dropdown text-nowrap">
        <a class="nav-link dropdown-toggle" href="substr.html#" id="dropdownlink-dev" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Dev</a>
        <div class="dropdown-menu" aria-labelledby="dropdownlink-dev">
          <a class="dropdown-item" href="https://perldoc.perl.org/blead/functions/substr">blead</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.39.6/functions/substr">5.39.6</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.39.5/functions/substr">5.39.5</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.39.4/functions/substr">5.39.4</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.39.3/functions/substr">5.39.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.39.2/functions/substr">5.39.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.39.1/functions/substr">5.39.1</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.38.0-RC2/functions/substr">5.38.0-RC2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.38.0-RC1/functions/substr">5.38.0-RC1</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.11/functions/substr">5.37.11</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.10/functions/substr">5.37.10</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.9/functions/substr">5.37.9</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.8/functions/substr">5.37.8</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.7/functions/substr">5.37.7</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.6/functions/substr">5.37.6</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.5/functions/substr">5.37.5</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.4/functions/substr">5.37.4</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.3/functions/substr">5.37.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.2/functions/substr">5.37.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.1/functions/substr">5.37.1</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.37.0/functions/substr">5.37.0</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.11/functions/substr">5.35.11</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.10/functions/substr">5.35.10</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.9/functions/substr">5.35.9</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.8/functions/substr">5.35.8</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.7/functions/substr">5.35.7</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.6/functions/substr">5.35.6</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.5/functions/substr">5.35.5</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.4/functions/substr">5.35.4</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.3/functions/substr">5.35.3</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.2/functions/substr">5.35.2</a>
          <a class="dropdown-item" href="https://perldoc.perl.org/5.35.1/functions/substr">5.35.1</a>
          <a class="dropdown-item active" href="substr.html">5.35.0</a>
        </div>
      </li>
      <li class="nav-item dropdown text-nowrap">
        <a class="nav-link dropdown-toggle" href="substr.html#" id="dropdownlink-nav" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Documentation</a>
        <div class="dropdown-menu" aria-labelledby="dropdownlink-nav">
          <a class="dropdown-item" href="../perl.html">Perl</a>
          <a class="dropdown-item" href="../perlintro.html">Intro</a>
          <a class="dropdown-item" href="../perl.html#Tutorials">Tutorials</a>
          <a class="dropdown-item" href="../perlfaq.html">FAQs</a>
          <a class="dropdown-item" href="../perl.html#Reference-Manual">Reference</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="../perlop.html">Operators</a>
          <a class="dropdown-item" href="../functions.html">Functions</a>
          <a class="dropdown-item" href="../variables.html">Variables</a>
          <a class="dropdown-item" href="../modules.html">Modules</a>
          <a class="dropdown-item" href="../perlutil.html">Utilities</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="../perlcommunity.html">Community</a>
          <a class="dropdown-item" href="../perlhist.html">History</a>
        </div>
      </li>
    </ul>
    <ul class="navbar-nav">
      <script>
        function set_expand (expand) {
          var perldocdiv = document.getElementById('perldocdiv');
          var width = window.getComputedStyle(perldocdiv).getPropertyValue('max-width');
          var expanded = (width == '' || width == 'none') ? true : false;
          if (expand === null) {
            expand = !expanded;
          }
          if ((expand && !expanded) || (!expand && expanded)) {
            perldocdiv.style.setProperty('max-width', expand ? 'none' : '960px');
            var button_classlist = document.getElementById('content-expand-button').classList;
            if (expand) {
              button_classlist.add('btn-light');
              button_classlist.remove('btn-outline-light');
            } else {
              button_classlist.add('btn-outline-light');
              button_classlist.remove('btn-light');
            }
          }
          return expand;
        }
        function toggle_expand () {
          var expand = set_expand(null);
          document.cookie = 'perldoc_expand=' + (expand ? 1 : 0) + '; path=/; expires=Tue, 19 Jan 2038 03:14:07 UTC';
        }
        function read_expand () {
          return document.cookie.split(';').some(function (item) { return item.indexOf('perldoc_expand=1') >= 0 });
        }
        if (document.readyState === 'loading') {
          document.addEventListener('DOMContentLoaded', function () {
            if (read_expand()) {
              set_expand(true);
            }
          });
        } else if (read_expand()) {
          set_expand(true);
        }
      </script>
      <button id="content-expand-button" type="button" class="btn btn-outline-light d-none d-lg-inline-block mr-2" onclick="toggle_expand()">Expand</button>
    <ul>
    <form class="form-inline" method="get" action="https://perldoc.perl.org/5.35.0/search">
      <input class="form-control mr-3" type="search" name="q" placeholder="Search" aria-label="Search">
    </form>
  </div>
</nav>

    <div id="wrapperlicious" class="container-fluid">
      <div id="perldocdiv">
        <div id="links">
          <a href="../functions.html">functions</a>
            / <a href="substr.html">substr</a>
          <div id="more">
            (<a href="substr.txt">source</a>,
            <a href="CORE.html#substr-EXPR,OFFSET,LENGTH,REPLACEMENT">CPAN</a>)
          </div>
        </div>
        <div class="leading-notice">
          You are viewing the version of this documentation from Perl 5.35.0.
            This is a development version of Perl.
        </div>
      <dl>

<dt id="substr-EXPR,OFFSET,LENGTH,REPLACEMENT"><a class="permalink" href="substr.html#substr-EXPR,OFFSET,LENGTH,REPLACEMENT">#</a><a id="substr"></a><a id="substr-EXPR-OFFSET-LENGTH-REPLACEMENT"></a>substr EXPR,OFFSET,LENGTH,REPLACEMENT     </dt>
<dd>

</dd>
<dt id="substr-EXPR,OFFSET,LENGTH"><a class="permalink" href="substr.html#substr-EXPR,OFFSET,LENGTH">#</a><a id="substr1"></a><a id="substr-EXPR-OFFSET-LENGTH"></a>substr EXPR,OFFSET,LENGTH</dt>
<dd>

</dd>
<dt id="substr-EXPR,OFFSET"><a class="permalink" href="substr.html#substr-EXPR,OFFSET">#</a><a id="substr2"></a><a id="substr-EXPR-OFFSET"></a>substr EXPR,OFFSET</dt>
<dd>

<p>Extracts a substring out of EXPR and returns it. First character is at offset zero. If OFFSET is negative, starts that far back from the end of the string. If LENGTH is omitted, returns everything through the end of the string. If LENGTH is negative, leaves that many characters off the end of the string.</p>

<pre><code>my $s = &quot;The black cat climbed the green tree&quot;;
my $color  = substr $s, 4, 5;      # black
my $middle = substr $s, 4, -11;    # black cat climbed the
my $end    = substr $s, 14;        # climbed the green tree
my $tail   = substr $s, -4;        # tree
my $z      = substr $s, -4, 2;     # tr</code></pre>

<p>You can use the <a href="substr.html"><code>substr</code></a> function as an lvalue, in which case EXPR must itself be an lvalue. If you assign something shorter than LENGTH, the string will shrink, and if you assign something longer than LENGTH, the string will grow to accommodate it. To keep the string the same length, you may need to pad or chop your value using <a href="sprintf.html"><code>sprintf</code></a>.</p>

<p>If OFFSET and LENGTH specify a substring that is partly outside the string, only the part within the string is returned. If the substring is beyond either end of the string, <a href="substr.html"><code>substr</code></a> returns the undefined value and produces a warning. When used as an lvalue, specifying a substring that is entirely outside the string raises an exception. Here&#39;s an example showing the behavior for boundary cases:</p>

<pre><code>my $name = &#39;fred&#39;;
substr($name, 4) = &#39;dy&#39;;         # $name is now &#39;freddy&#39;
my $null = substr $name, 6, 2;   # returns &quot;&quot; (no warning)
my $oops = substr $name, 7;      # returns undef, with warning
substr($name, 7) = &#39;gap&#39;;        # raises an exception</code></pre>

<p>An alternative to using <a href="substr.html"><code>substr</code></a> as an lvalue is to specify the replacement string as the 4th argument. This allows you to replace parts of the EXPR and return what was there before in one operation, just as you can with <a href="splice.html"><code>splice</code></a>.</p>

<pre><code>my $s = &quot;The black cat climbed the green tree&quot;;
my $z = substr $s, 14, 7, &quot;jumped from&quot;;    # climbed
# $s is now &quot;The black cat jumped from the green tree&quot;</code></pre>

<p>Note that the lvalue returned by the three-argument version of <a href="substr.html"><code>substr</code></a> acts as a &#39;magic bullet&#39;; each time it is assigned to, it remembers which part of the original string is being modified; for example:</p>

<pre><code>my $x = &#39;1234&#39;;
for (substr($x,1,2)) {
    $_ = &#39;a&#39;;   print $x,&quot;\n&quot;;    # prints 1a4
    $_ = &#39;xyz&#39;; print $x,&quot;\n&quot;;    # prints 1xyz4
    $x = &#39;56789&#39;;
    $_ = &#39;pq&#39;;  print $x,&quot;\n&quot;;    # prints 5pq9
}</code></pre>

<p>With negative offsets, it remembers its position from the end of the string when the target string is modified:</p>

<pre><code>my $x = &#39;1234&#39;;
for (substr($x, -3, 2)) {
    $_ = &#39;a&#39;;   print $x,&quot;\n&quot;;    # prints 1a4, as above
    $x = &#39;abcdefg&#39;;
    print $_,&quot;\n&quot;;                # prints f
}</code></pre>

<p>Prior to Perl version 5.10, the result of using an lvalue multiple times was unspecified. Prior to 5.16, the result with negative offsets was unspecified.</p>

</dd>
</dl>


      </div>
      <div id="footer">
        <p>Perldoc Browser is maintained by Dan Book (<a href="https://metacpan.org/author/DBOOK">DBOOK</a>). Please contact him via the <a href="https://github.com/Grinnz/perldoc-browser/issues">GitHub issue tracker</a> or <a href="mailto:dbook@cpan.org">email</a> regarding any issues with the site itself, search, or rendering of documentation.</p>

<p>The Perl documentation is maintained by the Perl 5 Porters in the development of Perl. Please contact them via the <a href="https://github.com/Perl/perl5/issues">Perl issue tracker</a>, the <a href="https://lists.perl.org/list/perl5-porters.html">mailing list</a>, or <a href="https://kiwiirc.com/client/irc.perl.org/p5p">IRC</a> to report any issues with the contents or format of the documentation.</p>


      </div>
    </div>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.slim.min.js" integrity="sha512-/DXTXr6nQodMUiq+IUJYCt2PPOUjrHJ9wFrqpJ3XkgPNOZVfMok7cRw6CSxyCQxXn6ozlESsSh1/sMCTF1rL/g==" crossorigin="anonymous"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.1/umd/popper.min.js" integrity="sha512-ubuT8Z88WxezgSqf3RLuNi5lmjstiJcyezx34yIU2gAHonIi27Na7atqzUZCOoY4CExaoFumzOsFQ2Ch+I/HCw==" crossorigin="anonymous"></script>
    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js" integrity="sha384-B4gt1jrGC7Jh4AgTPSdUtOBvfO8shuf57BaghqFfPlYxofvL8/KUEfYiJOMMV+rV" crossorigin="anonymous"></script>
    <script src="../../highlight.pack.js"></script>
    <script>hljs.highlightAll();</script>
  </body>
</html>
